# HVAC Load Duct Calc — BTU, Psychrometric, Ref Tool

> BTU, Psychrometric, Ref Tool (iPhone/iPad app by 剑挥 吴.)

- Source: https://appshunter.io/ios/app/hvac-load-duct-calc/id6771655877 (this page in markdown: same URL + `.md`)
- Developer: [剑挥 吴](https://appshunter.io/developer/1889796997)
- Category: Reference, Utilities
- Price: $3.99
- Age rating: 4+
- Requires: iOS 15.1 · 22 MB
- Languages: American English
- Released: 2026-05-26
- Data updated: 2026-05-29
- User reviews in markdown: https://appshunter.io/ios/app/hvac-load-duct-calc/id6771655877/reviews.md

## What is HVAC Load Duct Calc?

HVAC Load Duct Calc is the all-in-one toolkit for licensed HVAC technicians and engineers. Designed for field professionals who need fast, accurate calculations without internet access.
 
KEY FEATURES:

1. BTU Heat Load Calculator
- Calculate heating and cooling loads for any room
- Input room dimensions, insulation type, and temperature difference
- Automatic BTU-to-ton conversion
- Supports both heating and cooling scenarios

2. Duct Size Calculator
- Convert CFM to round duct diameter
- Get recommended maximum velocity by system type (residential, commercial, industrial)
- Round-to-rectangular duct conversion
- Calculate actual air velocity and equivalent diameter

3. Refrigerant Reference Data
- 8 common refrigerants including R-410A, R-32, R-134a, R-22, R-404A, R-407C, R-290, and R-454B
- Properties: boiling point, critical temperature and pressure
- ODP and GWP environmental data
- Safety classification for each refrigerant

4. Psychrometric Calculator
- Input dry bulb temperature and relative humidity
- Calculate dew point, wet bulb temperature
- Get enthalpy and humidity ratio values
- All calculations use standard ASHRAE formulas

5. Unit Converter
- Temperature: F, C, K
- Pressure: PSI, kPa, bar, inHg, atm
- Length: ft, m, in, cm
- Power: BTU/hr, kW, HP, tons, Watts
- Flow: CFM, L/s, m3/hr, GPM
- Energy: BTU, kWh, MJ, therms

WORKS COMPLETELY OFFLINE
No internet connection required. All calculations are performed locally on your device. No data is collected or transmitted.

BUILT FOR PROFESSIONALS
- Clean, easy-to-read interface designed for field use
- Large input buttons for use with gloves
- Instant results with professional accuracy
- Based on standard HVAC engineering formulas

HVAC Load Duct Calc is a one-time purchase with no subscriptions, no ads, and no in-app purchases. Pay once, use forever.


## Version history (last 1 release)

### 1.0 — 2026-05-27

No release notes.

## More apps by 剑挥 吴

- [AsiaNav GPS](https://appshunter.io/ios/app/asianav-gps/id6763953869)

All apps by 剑挥 吴: https://appshunter.io/developer/1889796997

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-05-29.*